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Thermodynamic investigation of the CaOAl2O3CaSO4K2OH2O system at 25°C

1993; Elsevier BV; Volume: 23; Issue: 5 Linguagem: Inglês

10.1016/0008-8846(93)90180-h

1873-3948

D. Damidot, F. P. Glasser,

Concrete and Cement Materials Research

An equilibrium phase diagram has been calculated for the CaOAl2O3CaSO4K2OH2O system at 25°C for several KOH concentrations. These KOH concentrations were chosen to relate to cement pore fluid compositions and published experimental data. In addition to the hydrates found in the CaOAl2O3CaSO4H2O system, syngenite and K2SO4 have to be taken into account. Thus new invariant points and boundary curves are defined for high potassium and sulphate concentrations. The general features of the system at higher temperatures, to 100°C, are outlined: above 40°C, the pentasalt, (CaSO4)5.K2SO4.H2O, becomes a stable phase.